Techniques like cavity ring-down spectroscopy, frequency modulation spectroscopy, and comb-referenced spectroscopy enable precision measurements of molecular gases. These techniques are used regularly in the near-infrared, where light sources are widely available. Engineering and software advances now provide convenient access to the 2 – 4 µm spectral region with high power, wide tuning, and narrow linewidth. In this webinar, we will demonstrate that a CW Optical Parametric Oscillator, TOPTICA's TOPO, can unlock the potential for research in the molecular stretching region of the spectrum.